LONDON, April 19 (Reuters) - Acacia Mining reported a near 50 percent fall in first quarter earnings on Thursday after reducing operations at its flagship gold mine in Tanzania amid a tax dispute with the government.

Acacia, a unit of Canada's Barrick Gold and Tanzania's largest gold miner, said its gold production fell 45 percent in the first quarter from a year earlier to 120,981 ounces, mainly due to lower output at its flagship Bulyanhulu mine.

Acacia's London-listed shares skidded 8.8 percent to 141 pence by 0919 GMT and have now tumbled more than 70 percent since Tanzania introduced a ban on concentrate exports in March 2017.

The company stuck to its full-year targets, targeting output of between 435,000-475,000 ounces, or at least 38 percent lower than 2017, at a cost of $935-985 per ounce.

Adjusted earnings before interest, taxes, depreciation and amortisation (EBITDA) for the three months to March 31 fell to $44 million from $82 million a year earlier, Acacia said.

It was forced to reduce operations at Bulyanhulu last year because of the tax dispute.

The miner has begun to value its Tanzanian operations for a potential sale after expressions of interest from Chinese buyers, it said in February.

Discussions between parent Barrick and the government to resolve both Tanzania's export ban on concentrates and the tax dispute are ongoing, Acacia said.

Barrick struck a deal in October with the government that was supposed to resolve the tax dispute. It would see Acacia pay $300 million to the government, hand over a 16 percent stake in its mines and split 'economic benefits' from operations.

However, Acacia has said any agreement would need to be reviewed by its board and expects a detailed version of the deal within the first half of the year.

Acacia is conducting a study this year on Bulyanhulu to find the best way to eventually re-open the mine.

"If the settlement agreement is in place, which we certainly expect it to be, then you would look at re-opening Bulyahulu sometime in 2019 and ramping it up to full scale in 2020 and 2021," interim CEO Peter Geleta told a conference call following the results.

Jeffries' analyst Alan Spence said Acacia's EBITDA figures fell slightly short of expectations but there were no surprises in the rest of the results.

"Given the situation I think they have done a good job of managing the risk," he said, referring to Acacia's ability to maintain cash and bolster its balance sheet with the sale of a non-core asset in December.

The company's cash balance as of March 31 was $107 million, representing a 33 percent rise from the end of December but down by more than 62 percent from a year ago. (Reporting by Zandi Shabalala; editing by Jason Neely and Susan Fenton)